WASHINGTON – A panel of legal experts agreed that the 2001 Authorization of the Use of Military Force (AUMF) covers President Obama’s move against the Islamic State of Iraq and al-Sham (ISIS) because it has no expiration date or geographic limits.

Speaking at the Heritage Foundation, Steven Bradbury, a partner at Dechert LLP who served in the office of legal counsel in the Department of Justice during the George W. Bush administration, said the 2001 AUMF gives the president “very broad authority” to use military action against ISIS.

“There is a very strong argument that the president is correct that the 2001 AUMF does continue to give the president statutory authority, approved by Congress, to carry out this continuing war on terror, including against ISIS both in Iraq and Syria,” he said.

Bradbury noted that “ISIS is essentially al-Qaeda” because it is the successor organization to the group led by Abu Musab al-Zarqawi, which carried out attacks on coalition forces, conducted suicide attacks on civilian targets, and beheaded hostages in Iraq.

“The president has authority under the 2001 AUMF to determine that ISIS is a reconstituted version of the al-Qaeda organization,” he said.

Top administration officials have argued that their actions against the Islamic State are covered by the 2001 AUMF that was passed after the Sept. 11 terrorist attacks. The authorization provides for the use of force against al-Qaeda, the Taliban, and associated groups posing an imminent threat to U.S. interests. The administration also sees the 2002 AUMF, which authorized the Iraq War, as an alternative statutory authority basis, the New York Timesreported.

In a letter to Congress released after his remarks last month, Obama said he was acting “pursuant to my constitutional and statutory authority as Commander in Chief (including the authority to carry out Public Law 107-40) and as Chief Executive, as well as my constitutional and statutory authority to conduct the foreign relations of the United States.”

Robert Chesney, a law professor at the University of Texas-Austin and a member of the president’s Detention Policy Task Force, says he finds the Obama administration’s legal argument for strikes against ISIS plausible but unpersuasive.

“Al-Qaeda in Iraq was the paradigm example of an al-Qaeda cell that emerged as a standalone associated force engaged in hostilities against the United States; at that point in time both the 2001 and 2002 AUMF covered it,” Chesney said.

The rifts between ISIS and al-Qaeda and the beheadings of two American journalists have “muddied the waters” of a threat to the U.S. or its allies, he said.

Nevertheless, Chesney said a legal case could be made for U.S. military action on the basis that ISIS-controlled territory could be used as a sanctuary for terrorists directly threatening the U.S.

“Over time it doesn’t take a rocket scientist to see that the existence of ISIS as a territorial unit sooner or later could provide the type of cover that Afghanistan once provided to al-Qaeda,” he said. “That is a deep strategic threat, but it is harder to articulate because it is much more speculative.”

The U.S. and partner allies began airstrikes against ISIS in Syria, also known as the Islamic State or ISIL, last month.

The airstrikes also targeted a group, known as Khorasan, that U.S. officials have described as a network of seasoned al-Qaeda fighters with battlefield experience mostly in Pakistan and Afghanistan.